Dosage effects of Ds
--Manfred Heinlein and Peter Starlinger

Previous experiments employing the Ds9 element of the wx-m9Ds allele (which differs from Ac in wx-m9 by a deletion of 194 bp) have shown that the frequency of Ds9 excisions is not only dependent on the dosage of the transactivating Ac element (we used the Ac element present in the bz-m2 allele of the Bz1 gene) but also on its own dosage. We found that the Ds9 element is more often excised if inherited from the male than if inherited from the female and that, if homozygous, the Ds9 element is excised with a frequency which by far exceeds the sum of the frequencies obtained with one and two Ds elements. Accordingly, the maternally and paternally transmitted Ds9 elements seem to be much better substrates for excision if combined in one nucleus than if separated. These results were independent of the dosage of the transactivating Ac element.

We have repeated the same kind of experiment with the Ds element of the bz-m2(DI) allele and used either one, two or three doses of the Ac element present in the wx-m7 allele or of the Ac element present in the wx-m9 allele for transactivation. The patterns seen on the ears are currently being evaluated. 


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